Slugs and snails will go after the tender plants first, they are hard to totally get rid of. I use a lot of bait and go out in the morning and evening and especially if it is raining and hand pick them. They hide under pots, under mulch and in the tall grass and weeds. For every one you find there are probably a hundred that you missed.
Toads, hens and ducks are also good at keeping the slug population down. I don't have a toad, but I have dealt with hens before. They go a good job of eating grasshoppers, geckos, slugs and snails, but they will also eat the lettuce and scratch up seeds and seedlings, so if you have a hen you will need to either pen off some of the plants or watch the hen when she is working, or use the chicken tractor.
Happy gardening in Hawaii. Gardens are where people grow.